The present invention relates to a support apparatus for a form roller in a printing press.
In an offset printing press, sometimes, a blurred portion appears in part of a solid printing area, that is, a printing trouble so-called ghost occurs. As a countermeasure for preventing the ghost, in a conventional roller support apparatus, a compression coil spring is interposed in an ink form roller. The ink form roller is slid in the axial direction by utilizing the frictional force with respect to an oscillating roller which is in contact with the ink form roller.
U.S. Pat. No. 4,739,703 proposes an inking apparatus in which an ink form roller is constituted by a roller shaft, a roller main body fitted on the roller shaft to be rotatable and slidable in the axial direction, an oscillating stroke adjusting member threadably engaging with the roller shaft, and a compression coil spring resiliently interposed between the oscillating stroke adjusting member and roller main body.
In the conventional roller support apparatus described above, after the ghost countermeasure is taken making allowing the ink form roller to be slidable in the axial direction, the slide motion of the ink form roller in the axial direction must be regulated. Therefore, after the ghost countermeasure is taken, the oscillating stroke adjusting member is screwed in to compress the compression coil spring, so that the resilience of the compression coil spring is regulated.
With a pattern that does not require a ghost countermeasure, if the ink form roller is slid in the axial direction, contamination caused by ink attaching to a non-image area, that is, scumming occurs. In this case, the slide motion of the ink form roller in the axial direction must also be regulated. Therefore, with a pattern that does not require a ghost countermeasure, the oscillating stroke adjusting member is screwed in to compress the compression coil spring thoroughly, so that the resilience of the compression coil is regulated.
The operation of screwing in the oscillating stroke adjusting member against the resilient force to a position where the resilience of the compression coil spring is regulated requires a large screwing force. This poses a heavy load on the operator. As the oscillating stroke adjusting member is screwed in, the roller shaft which is supported rotatably also rotates undesirably, resulting in poor workability. To solve these problems, the roller shaft must be removed from the printing press temporarily, and then the screwing operation must be performed. When the operation is ended, the roller shaft must be attached to the printing press again. As a result, the operation becomes cumbersome, and a long operating time is needed.